Ship&#39;s navigational light



March 27, 1956 c R 2,740,038

SHIPS NAVIGATIONAL LIGHT Filed Sept. 25. 1952 FIG. 2

STBD SIDE LIGHT INVENTOR JOHN CARRIE A F|G.3 BY 3% 7M ATTORNEYS SHIPS NAVIGATIONAL LIGHT John Carrie, Arlington, Va. Application September 25, 1952, Serial No. 311,555 4 Claims. (Cl. 240-75) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties theron or therefor.

This invention relates to ships navigational lights and more particularly to running lights used on ships. The type of light fixture disclosed herein utilizes a primary source of light and a highly polished reflecting rod for radiating rays of light in an arc, the angle of which is defined by a pair of screens positioned on the ship.

The characteristics of a ships navigational lights are controlled by statute, the latter being commonly known as the International Rules and Regulations for Preventing Collisions at Sea. These rules require that each of the ships navigational lights provide an arc of light of definite value, color and height, and that they be visible throughout a prescribed distance, depending on where the light is situated on the ship.

The fixtures of the prior art satisfy the above-mentioned requirements in the rules, but with one notable exception, namely, the arc of emitted light of the fixtures of the prior art is not of a definite value. The variance in the value or size of the arc is caused by the relative position of the lens-enclosed lamp or bulb with respect to the screens which are used for confining the arc to a particular sector adjacent the ship.

It is common practice to position the socket for the bulb at the intersection or apex of a pair of planes lying in the face of each of the screens in the fixture. The filament of the bulb is therefore in alignment with the screens and the arc thereby subscribed conforms to the requirements set forth in the rules for this particular fixture. However, in order to obtain watertight integrity, the bulb is enclosed in a lens having a top opening closed by a cap which is held in place by a plurality of tie-rods exterior to the lens. It is evident from this that the outermost part of the lens is closer to the opening formed by the screens than the filament of the bulb; the result being that the arc is actually increased in length, since an observer could move outside of the angle formed by the screens, and although he could not see the filament from this point, the lens and the light radiated therefrom would be clearly visible to him. This situation is aggravated by the fact that the tie rods also radiate light and a tangential glow surrounds the burning light during the hours of darkness.

In order to eliminate the above-described deficiencies, larger, and therefore more expensive, screens have been incoiporated in the prior art fixtures, and although this improves the angle of cut-off of light, it fails to solve the problem of having one are of definite value.

The present invention eliminates the disadvantages set forth above by converting the sole source of light of prior art fixtures into a primary source and introduces a verticalline secondary light source into the structure. This vertical-line secondary light source takes the form of a mirrorlike silvered glass tube positioned outward of the primary light source for reflecting the light in such a fashion that an unvarying and accurate cut-oil angle is achieved. This vertical-like secondary source can be designated, for convenience, as a reflector.

It is therefore an object of the invention to provide a new and eflicient ships navigational light.

A further object is the provision of a light covering a prescribed arc of visibility over a varying range of distance.

Another object of the invention is the provision of a light having short screens thereby resulting in a smaller, lighter and less costlier fixture.

A still further object is the addition of a reflecting rod for clearly establishing the cut-off angle of light emitted by the light source.

With these and other objects in view, as will herein after more fully appear, and which will be more particularly pointed out in the appended claims, reference is now made to the following description taken in connection with the accompanying drawings in which:

Figure l is a perspective view of a ships navigational light embodying the principles of the invention, the light being adapted to receive a suitable screen according to the particular location of the light on a ship;

Figure 2 is a sectional view taken on lines IIII of Figure 1, showing a screen adapting the light for use as a starboard side light;

Figure 3 is a sectional view similar to Figure 2, but having a screen adapting the light for use as a stern light; and

Figure 4 is a sectional view similar to Figure 2, but having a screen adapting the light for use as a masthead light.

characters designate like or corresponding parts throughout the several views, there is shown in Figure 1 a running light comprising a lamp 10 threaded into a socket 12. The means for supplying power to this bulb comprises electrical conductors extending from a suitable source of power located in the ship. Surrounding the bulb is a colored or transparent or translucent lens 14 mounted vertically between a metal base 16 and a cap 18 each of which is provided with rubber gaskets 20 thereby providing a water-tight seal at the ends of the cylindrical lens. In order to secure the water-tight seal integrity as well as to hold the entire assembly together, brass tie rods 22 external to the lens are used to clamp the cap, lens and base of the fixture into a complete unit. This lamp assembly is adapted to be situated within metal screens 24. These screens are usually made of two parts, but may be integral, as shown in this drawing. The screen is shaped as shown; and the surface of the screen facing the lamp are generally painted of the same color as the translucent shade or lens which encloses the lamp 10. A metal supporting plate 26 is welded or otherwise secured to a part of the ships structure for supporting the lamp hereinabove described.

An important feature of the invention is the positioning of a reflecting tube or rod 28 around one of the brass tie-rods 22 as a secondary source of light. This reflecting tube or reflector 28 is internally silvered so as to create a mirror-like surface for reflecting light from lamp 10. As shown in these figures, the tie-rod 22 which accommodates the reflecting tube 28 is situated forwardly of the lamp 10 and is accurately placed in position so as to achieve a proper light cut-off at the ends of each of the screens. In general, as is apparent from Figs. 2, 3 and 4, the tube 28 lies slightly outward of a line extending from the edge of the screen and substantially tangent to the lens 14. As shown in each of Figures 2, 3 and 4 the metal screens 24 are properly arranged with respect to the lamp assembly for light cut-off, and may be formed as smooth curves, as shown in Figs. 3 and 4, and may have Referring now to the drawing, wherein like reference- 3 added-cubofl portions as shown-in the screen of Figure-2 where a projecting portion '30 is shown for achieving a proper cut-off of light at an angle that is required for the particularrunningdight'dn the-sni in Figures 2, 3- sn'd' 4 insures-re resented by characters A through G show the various angles of light, directand reflected,' that arernade" b the fixtures, direct light 'being indicated by --a1ternatin relativelys ho'rt and long lines, and'refiected light byrelatively long lines alternating with pairs of short lines. analysisof these angles "and the arcs subtended thereby, will show a strict compliance with theRulessince the'angle-of light emitted from each fixture is or definite valuewhidhr'esiiltsfrom a sharp cutoff of light. A chart of the variou'sangle's andranges is as follows:

lnall figures, n represents the correct angle oflight, both direct and reflected, visible throughout the prescribed rangeiro'm the ship. The-fixture is designed with this angle and satisfies the International Rules mentioned above.

in Figures 3 and 4, thean'gles are:

B--Maximu'm angl'e'of light emitted from the primary source, including thebulb'ifl'andlens -14.

fC- Angle of direct light visible to the horizon.

D Non-overlappin'g angles of light reflected solely by the reflector comprising the *tubeZS.

E-An'gles of 'directand'reflected light which add to C to result in-an'gleA.

With respect to Fig. 2 the angles are:

F Angle "of direct light visible to the horizon.

'G--*Ang1es of direct and reflected light thatadd'to F to result in angle A.

lrior investigations-haveshown that in navigational lam fixtures dfthe prior-that is, -'a fixture not utilizing a reflecting rod, an observer positioned within '1000 yards of the li ht sdurce could actually "see the light even though he'w'as outside-or the an'gle 'or are which the fixture was designed to encompass. This occurred because light was'reflected from the brass tie rod immediately in frontor outward of the fixture, arid-also, because the tangentialfglow fromthe lenswa's of sufficient intensity within this lOQQ yard rangeto give the appearance of an actual lamp. However, as the observer moved away from the fixture, thereby increasing the distance from the light source, the reflection' from thetie rodin the forward part of the lens, '"-andthe 'tangentialglow, was not of sufficient intensityto be diseemabie'atgreaterran es. In order to see the lightjit was "tnennecessary 'to -move within the angle defined by ih'e'scree'ns where the lens could be observed. Thereforejtheefrorofarc visibility created by the prior art fixtures is'such that'it is greater'where the error should be the 5 least, "that is, atsho'rt ranges.

iIn nightbper'ations of ships at sea, the navigational lights are relied on "as 'the sole source for determining the true bearing of "one ship from'an'otherand thereby roughly determining, when additional navigational aids are not used, the course the various vessels are steering. It is believed obviousthat'the-impottance of light fixturesflruly showing the arc of light for which they were designed, might very Well determine the safety of the ship when operatingduringdarkriess.

The fixture itself has -b'ee'n subordinated-to a position well inside the screen where iffunctionsas a primary light source "for distributing r'aysof light over the -major and central portion "of the arc. Thepriniary light source also serves to illuminate 'the-vertieal-line reflector, and this reflector-directs lighfirayspast' theedges of the screens into that portion of theatre ttia't'is not covered by light direct "from the primary "source. These "light rays from the secondary source are always in predetermined relation relative to the edges of the screens, because of the accuracy with which the single tube 28 can be repeatedly placed in the fixture. Its position inside the screen is such, however, that it can in no way influence the cut-off angles which determine the boundaries and hence the size of the arc. This important function is controlled entirely by the vertical-line reflecting rod which is placed at the critical position formerly occupied by the lamp. Since it presents a vertical-line of light of unvarying width, it creates a cut-0E angle at each end of the arc of visibility and the value of this angle is controlled by the proper design of the screens.

This invention eliminates the errors inherent "in prior navigational lamp fixtures and assures the emission of an arc of light of proper value in addition to being reliable and accurate. I I

"Various modifications are contemplatedand'may obviousl'y be'r'esort'e'd' to by others skilled in the a'rfwi'thout departing fro'm'the spirit, and scope or the invention, as hereinafter defined by the appended claims,as only 'a'pleferr'ed embodiment'thereof has been disclosed.

What is claiine'dis:

1. In a navigational lamp fixture comprising a lamp socket, a lamp in said socket, a translucent lens enclosing said lamp, base and cap means respectively"po'sitiorid on each end'of said lens thereby forming a water-tight unit, a 'plur'alityof tie-rods exterior to said ledssecuring said base tosaid cap, an open screen having'a predetermined opening therein mounted adjacent said lamp fixture'and reflecting means mounted'on a'tie' r'od outward ofsaid lens and away from said screen forrefic'ctin'g light rays toward the "ends of an arc defined b'ythe opening of said screen, said reflecting means c'omprisinga'hollo'w glass rod having an internally silvered'surface forming a' mirror like finish onsaidrod.

2. A navigational lamp fixture for providing a'sub's'tan' tially constant prescribed arc of 'visibility'over a prescribed range of distances comprising, a screenha'vin'g angularly disposed panels of predetermined dimensions in the direction ofsaid prescribed are integral at "one end and open at the opposite ends, said opening defining a predetermined are, a light source mounted adjacent'the vertex'and along the bis'ector of the angle formed-by said panels, and a substantially vertical-line reflector mounted adjacentsaid vertex alongsaidbisector, outward ofsaid light 'sour'ce and away from said screen for-directing light toward the open ends of said 'screeu'to defizie' said'pr'escribed arc of visibility, the dimension of said panels from said verte'X'to said open ends for said'prescribed are being determined by the position "of "said reflector.

3. The combination according to'cl'airn -2 Whef'ein saitl light s'ource comprises a lamp, a translucentlen's encl'osing'sa'id lamp, base and cap means respectivelyp'ositiohe'd on each endof said lens, and a plurality of tie rods exteriortosaid-lens securing said base tosaid-cap,thereby formin'g'a watertight unit. 7

4. The cornbinati'onaccording to claim 3 wherein said vertical line reflector comprises a highly polished"holloiv rod 'm'ounted on one of said tie rods.

References Cited in the file of this patent UNITED STATES PATENTS Sherman Feb. 8, i876 

